监测并掌握城市排洪沟水体中致病菌的污染现状,对强化城市排洪沟的修复整理和常规性管理工作,提升污染突发事件中的预见预警能力和保障人居地周围的环境安全有着重要意义。以粪大肠菌群数为致病菌检测指标,通过五管发酵法对兰州市区不同功能区的主要排洪沟水体中粪大肠菌群进行了检测和分析。结果显示:水体中致病菌的污染程度较高,粪大肠菌群平均含量1.61×107个/L,最小2.3×105个/L,最大2.34×107个/L;文教区排洪沟致病菌污染最重,混合区次之,工业区污染较轻;根据GB 3838—2002《地表水环境质量标准》,利用单因子污染指数公式Pi=Ci/Si计算,污染最轻的深沟桥排洪沟水体中的粪大肠菌群数也已达到地表水环境质量V类标准的5.75倍。

The two-way indicator species analysis and the detrended correspondence analysis are adopted to classify and rank the quadrats of the secondary plant in the Hanquangou valley in Gansu province.The flora can be divided into different community types,and demonstrate the distributed pattern of the vegetation community in this region.Based on this result,the species richness index,the Simpson dominance index,the Shannon-Wiener diversity index and the Pielou evenness index are used to study the species diversity of different vegetation community types.The results shows that there are 7 community types,which represents the different restoration stages.The primary limiting factors are water and heat in specific region,Chashugou valley.From restora-tion stage Ⅰt oⅦ,as for the Simpson dominance index,tree layer,shrub layer and herb layer are approximately equal,the Shan-non-Wiener diversity index manifests as tree layer shrub layer herb layer,the Pielou evenness index manifests as tree layer herb layer shrub layer,and the species richness increase gradually.The species composition and the spatial structure of the community become complication gradually,and tend to be stable.

Based on the survey of community plots,The two-way indicator species analysis and the Detrended correspondence analysis were adopted to classify and rank the quadrats of the secondary forest in the eastern Qilian mountains in gansu province. To study the spatial distribution pattern of plant populations from the species structure and the ecological relationship of plant species,plant communities and environment in this region,and so as to obtained the forest secondary succession in different stages. The results show that there were 7 community types,the primary limiting factors were water and heat. The result of DCA ordination showed that dieffrent plant communities and their distributing area varied along the environmental gradients in the ordination grpah.The first axis of DCA denoted humidity gradient and the second axis of DCA denoted change of altiutde and temperature gradient. The results indicate that the succession law of the secondary forest was from aspen,however,with the passage of time,serclimax finally became the Qinghai Spruce.

The Xiaolongshan Nature Reserve is one of the Pinus armandii distribution areas in China.Based on large number of field surveys,study was carried out on ecological niches of the eight major populations of the Pinus armandii community,which is located in Xiaolongshan,Gansu Province,using the indexes such as the Levins and Shannon-Wiener′s ecological niche breadth,niche overlap index,and niche proportional similarity.Results show that the ecological niche breadth of the 8 plant populations follow the order of Pinus armandiiQuercus aliena var.acuteserrataLonicera lanceolataRhus verniciflusCrataegus kansuensisCastanea mollissimaQuercus liaotungensisTilia paucicostata.The population of Pinus armandii is the highest in Shannon-Wiener niche breadth,being 0.988 8,that of Quercus aliena var.acuteserrata follows,being 0.877 6,and that of Tilia paucicostata the lowest,being 0.352 9 only.The values of niche overlap of the populations in the community are generally low,which demonstrates low competition between most populations,but the niche overlap values of the dominant population of Pinus armandii with the other populations are relatively high,ranging between 0.079 1 and 0.101 3,whereas those of the other populations with that of Pinus armandii are relatively low,being in the range between 0.015 4 and 0.069 0.The overlap value is the highest between Pinus armandii and Castanea mollissima,being 0.101 3 and the lowest between Pinus armandii and Tilia paucicostata,being 0.079 1.There are 4 pairs of populations that have niche proportional similarity higher than 0.5 in value,accounting for 14.28%.They are Pinus armandii and Quercus aliena var.acuteserrata,Pinus armandii and Lonicera lanceolata,Quercus aliena var.acuteserrata and Lonicera lanceolata,and Quercus aliena var.acuteserrata and Rhus verniciflus.And the remaining 24 pairs are lower than 0.5,accounting for 85.72%,which demonstrates that the populations are mostly low in similarity of resource utilization.As one of the most important distribution areas for Pinus armandii in China,Xiaolongshan,the western section of the Qinling Mountains,is characterized by the ecological niche of a warm temperate coniferous forest.

Quercus aliena var.acuteserata is the main vegetation type of Xiaolongshan national nature reserve and its distribution pattern is one of the indexes to judge if the forest type recovers or not.In this paper,v/m ratio,negative binomial parameter,clumping index,cassie index and patch index are used to analyze the spatial pattern of Quercus aliena var.acuteserata forest at Xiaolongshan.The results show that the age structure of Quercus aliena var.acuteserata population is unreasonable at present,which belongs to stable population.The distribution pattern of this population takes the aggregation distribution,and the aggregation intensity is high,but it decreases with the increase of the maturity of the stands.

Based on the implementation of Tianbao Project,the paper gave an investigation on the species diversity and stability of the quercus aliena var.acuteserrata community.The conclusions were as follows:(1) Patrick abundance index was R=10.6,Shannon-Wiener index was H′=1.4222,Pielou index was Jsw =0.5450,Simpson index was C=0.4134.These datas showed the southern warm temperate zone's biodiversity characteristic as well as the regional features,which was between subtropical evergreen broad-leaved forest and broad-leafed deciduous forest in the north of warm temperate zone.(2)There were two distributed patterns of species diversity on M t.Xiaolong's sunny slope and shade slope.There were bigger diversity,evenness and richness on shade slope than that on the sunny slope.(3)As the development of community,diversity and abundance index had the similar variation.Conversely,that of evenness and dominance was different.It showed the different significance on ecology.(4) The quercus aliena var.acuteserrata community was built with quercus aliena var.acuteserrata species,which belonged to was stable.Compared with the earlier studies,the results proved that the implementation of Tianbao Project was scientific and effective.